The present invention relates to a method for manufacturing a rotor core of a rotary electric machine such as a motor and a generator.
A rotor core of an embedded magnet motor disclosed in Japanese Laid-Open Patent Publication No. 2007-20350 is manufactured as follows. That is, a lamination body 301 is first formed by laminating thin plate-like core pieces 302 each having elongated holes 310H as shown in FIG. 12. Then, a permanent magnet 305 is inserted and embedded in each of insertion holes 301H of the lamination body 301 so that a rotor core is manufactured.
Step-like position determining portions 313R, 313L for determining the position of each permanent magnet 305 are provided on both longitudinal ends of each elongated hole 310H of the core piece 302 to prevent the permanent magnet 305 from being displaced in the longitudinal direction of the elongated hole 310H. Therefore, when filling gaps S9, S10 between the inner wall of each insertion hole 301H of the lamination body 301 and the associated permanent magnet 305 with filling material such as plastic material after inserting each permanent magnet 305 in the associated insertion hole 301H, the permanent magnet 305 will not be displaced before the filling material hardens.
However, the position determining portions 313R, 313L provided in each elongated hole 310H of the core piece 302 increase the area of a magnetic passage. As a result, the amount of magnetic flux that leaks through the magnetic passage without flowing to the stator is increased. Thus, there is room for improvement in increasing the output torque of the motor.